The nut of the peanut (Arachis hypogaea) is covered in a red-pigmented testa. This material is removed in processing of peanuts for retail markets and for further processing. High quality peanut skins are available in large quantities from processing plants. Generally, this material is a waste by-product, although it is useful as a feed ingredient for livestock or poultry (see, e.g., West et al., 1993, J. Dairy Sci. 76:590-599; McBrayer et al., 1983, J. Anim. Sci. 56:173-183; Hale & McCormick, 1981, J. Anim. Sci. 53:1006-1010; Utley et al., 1993, J. Anim. Sci. 71:33-37; Atuahene et al., 1989, Brit. Poultry Sci. 30:289-293). Recent work identified peanut skins as a source for proanthocyanidins (see, e.g., Lou et al., 1999, Phytochem. 51:297-308), a group of chemicals known as the active properties in grape seed extract, marine pine bark, and other plants, which are widely touted as nutriceuticals for prevention of heart disease and other applications. Apparently, the potential value of peanut skins for medicinal or biological uses been studied only as regards treatment of chronic hemorrhage and bronchitis in Chinese herbal medicine (see, e.g., Jiangsu Xin Medical College, 1977, In: Dictionary of Chinese Materia Medics. Pub, by Shanghai Science and Technology Publisher, Shanghai China P. 2648), their high tannin content (see, e.g., Karchesy & Hemingway, 1986, J. Agr Food Chem 34: 966-970), antioxidant activity (see, e.g., Nepote et al., 2002, Grasas y Aceites, 53:391-395) and for inhibition of hyaluronidase (see, e.g., Lou, et al., 1999, Phytochem. 51:297-308). If components of peanut skins could be shown to impart useful veterinary or medical effects, the value of peanut skins could be significantly enhanced.
Broiler chicks are vaccinated at the hatchery for protection against a variety of diseases, including infectious bronchitis, Newcastle disease, Marek's disease, infectious bursal disease, coccidiosis, and other common viral diseases. Vaccination is commonly given by aerosol, injection, or by injection in ovo (see, e.g., Bermudez & Stewart-Brown, 2003, Disease prevention and diagnosis. In Diseases of Poultry, 11th edition. Ed. by Y. M. Saif, H. J. Dames, J. R. Glisson, A. M. Fadly, L. R McDougald, and D. E. Swayne. Iowa State Press, Ames Iowa, pp. 17-54; Ricks, et al. 1999, 1999, In ovo vaccination technology. Adv. Vet. Med. 41:495-515. Academic Press, San Diego Calif.). Protection against disease after vaccination is generally sufficient, but in many cases is sub-optimal due to interference with the immune system from other viruses, inadequate immunogenicity of the vaccine strains, and even pathogenicity of the vaccine strains (see, e.g., Bermudez & Stewart-Brown, 2003, Disease prevention and diagnosis. In Diseases of Poultry, 11th edition. Ed. by Y. M. Saif, H. J. Dames, J. R. Glisson, A. M. Fadly, L. R McDougald, and D. E. Swayne. Iowa State Press, Ames Iowa, pp. 17-54). Poor immune response may also be a result of bird genetics, for example, birds that are particularly poor T-cell responders. Adjuvants are not commonly used in broilers because of the possibility of adverse effects on production parameters, and damage to meat. Poor immunity against respiratory viruses leads to an increase in secondary infections and increased use of antibiotics for treatment. Previous work has identified substances, called immuno-modulators, that enhance the response of the host to specific antigens. Administration of these substances along with a vaccine or natural infection tends to cause the animal to develop a stronger immune response and more quickly, with less antigen (Schijns, 2000, Current Opin. Immunol. 12:456-463; Singh & Hagen, 1999, Natur. Biotechnol. 17:1075-1081). Coccidiosis and other diseases relying on stimulation of the cellular immune system might be better controlled if immune modulators were used in concert with the vaccine.
Coccidiosis in poultry is an excellent model for study of the use of immunomodulators in concert with live vaccines. Coccidiosis is a serious intestinal disease caused by protozoa of the genus Eimeria. In the US alone, coccidiosis costs the poultry industry hundreds of millions of dollars annually, including $ 100,000,000 spent on control measures (see, e.g., McDougald, 2003, Coccidiosis. In Diseases of Poultry, 11th edition, ed by Y. M. Saif, H. J. Barnes, J. R. Glisson, A. M. Fadly, L. R McDougald, and D. E. Swayne. Iowa State Press, Ames Iowa, pp. 974-990). Producers have traditionally controlled coccidiosis by extensive use of anticoccidial compounds as feed additives, used for prevention, but this approach is limited by emergence of drug resistance in field strains of coccidia (see, e.g., Chapman, et al. 2002, Int. J. Parasitol. 32:617-629) and by public outcry over perceived misuse of drugs in food animals. Producers are now turning to vaccination for control of coccidiosis (see, e.g., Williams, 2003, Avian Path. 31:317-353), as natural infections with coccidia in chickens tends to produce a strong, lasting protective response (see, e.g., Rose, 1987, Current Opin. Immunol. 12:456-463).
Coccidiosis and other diseases stimulate the cellular immune system in a complex manner, apparently mediated through CD4 lymphocytes, with little contribution by the B-cell lymphocytes (see, e.g., Lillehoj, 1998, Avian Dis. 37:731-740). The extent of protective immunity depends on several critical factors; the magnitude of the initial exposure, the species of Eimeria, and the bird's innate ability to mount T-cell responses. Under field conditions, the bird may be affected by viruses or other conditions which may induce immunodeficiency. Coccidiosis is mainly a disease of young birds, emphasizing the importance of early protection and rapid action of vaccines. In the vaccination of broilers, a vaccine should not adversely affect economic parameters of weight, feed conversion, skin pigmentation, or other carcass qualities. Broilers are generally grown for only a short time, being marketed at 5-8 weeks of age, giving the vaccine a short period in which to act. Some vaccines are known to depress growth and feed efficiency during the exposure period, leaving the bird little time to recover in the rapid growth stage. For this reason, milder (attenuated) strains of coccidia are being developed for use in vaccines (see, e.g., Long & Johnson, 1988, Avian Path. 17:305-314), but these have the disadvantage of being less immunogenic. Despite the possible disadvantages, pressures of modern consumer interests favors a move from chemoprevention to biological (vaccination) control of coccidiosis (see, e.g., Chapman et al., 2002, Int. J. Parasitol. 32:617-629).
Substances previously identified to stimulate the immune system for coccidiosis vaccine include Corynebacterum parvum, dimethyl dioctadecyl ammonium bromide, and complete Freund's adjuvant (see, e.g., Lillehoj et al, 1993, Avian Dis. 37:731-740), recombinant interferon gamma (Lowenthal et al., 1999, Vet. Immunol. Hnmunopathol. 72:183-188); vitamin E (see, e.g., Gore & Quereshi, 1997, Poultry Sci. 76:984-991) and recombinant bovine somatotrophin (see, e.g., Allen & Danforth, 1997, Poult. Sci. 76:1349-1354). These materials, while enhancing immunity to various degrees, have the disadvantage of negative effects on economic parameters.
There exists a need for a product which can be used concurrently with conventionally applied vaccines and hatchery practices, which improves the performance of vaccines without damaging hatchability or performance parameters of broiler chickens.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.